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We consider a shortest path problem, where the travel times on the arcs may vary with time and waiting at any node is allowed. Simple adaptations of the Dijkstra algorithm may fail to solve the problem, when discontinuities exist. We propose a new Dijkstra-like algorithm that overcomes these difficulties. 相似文献
24.
Kunde GJ Hsi WC Kunze WD Schüttauf A Wörner A Begemann-Blaich M Blaich T Bowman DR Charity RJ Cosmo A Ferrero A Gelbke CK Hubele J Immé G Iori I Kreutz P Lindenstruth V Lisa MA Lynch WG Lynen U Mang M Möhlenkamp T Moroni A Müller WF Neumann M Ocker B Ogilvie CA Peaslee GF Pochodzalla J Raciti G Rubehn T Sann H Seidel W Serfling V Sobotka LG Stroth J Stuttge L Tomasevic S Trautmann W Tsang MB Tucholski A Verde G Williams CW Zude E Zwieglinski B 《Physical review letters》1995,74(1):38-41
25.
Federico Iori Eleonora Luppi Ivan Marri D. Ninno Stefano Ossicini 《Journal of luminescence》2006,121(2):335-339
There are experimental evidences that doping control at the nanoscale can significantly modify the optical properties with respect to the pure systems. This is the case of silicon nanocrystals (Si-nc), for which it has been shown that the photoluminescence (PL) peak can be tuned also below the bulk Si band gap by properly controlling the impurities, for example by boron (B) and phosphorus (P) codoping. In this work, we report on an ab initio study of impurity states in Si-nc. We consider B and P substitutional impurities for Si-nc with a diameter up to 2.2 nm. Formation energies (FEs), electronic, optical and structural properties have been determined as a function of the cluster dimension. For both B-doped and P-doped Si-nc the FE increases on decreasing the dimension, showing that the substitutional doping gets progressively more difficult for the smaller nanocrystals. Moreover, subsurface impurity positions result to be the most stable ones. The codoping reduces the FE strongly favoring this process with respect to the simple n-doping or p-doping. Such an effect can be attributed to charge compensation between the donor and the acceptor atoms. Moreover, smaller structural deformations, with respect to n-doped and p-doped cases, localized only around the impurity sites are observed. The band gap and the optical threshold are largely reduced with respect to the undoped Si-nc showing the possibility of an impurity-based engineering of the Si-nc PL properties. 相似文献
26.
Guenther Fuellerer Karl F. Doerner Richard F. Hartl Manuel Iori 《European Journal of Operational Research》2010
This paper addresses an important combination of three-dimensional loading and vehicle routing, known as the Three-Dimensional Loading Capacitated Vehicle Routing Problem. The problem calls for the combined optimization of the loading of freight into vehicles and the routing of vehicles along a road network, with the aim of serving customers with minimum traveling cost. Despite its clear practical relevance in freight distribution, the literature on this problem is very limited. This is because of its high combinatorial complexity. 相似文献
27.
Olivia Pulci Elena Degoli Federico Iori Margherita Marsili Maurizia Palummo Rodolfo Del Sole Stefano Ossicini 《Superlattices and Microstructures》2010
First-principles calculations within density functional theory and many-body perturbation theory have been carried out in order to investigate the structural, electronic and optical properties of undoped and doped silicon nanostructures. We consider Si nanoclusters co-doped with B and P. We find that the electronic band gap is reduced with respect to that of the undoped crystals, suggesting the possibility of impurity based engineering of electronic and optical properties of Si nanocrystals. Finally, motivated by recent suggestions concerning the chance of exploiting Ge dots for photovoltaic nanodevices, we present calculations of the electronic and optical properties of a Ge35H36 nanocrystal, and compare the results with those for the corresponding Si35H36 nanocrystals and the co-doped Si33BPH36. 相似文献
28.
We consider difficult combinatorial optimization problems arising in transportation logistics when one is interested in optimizing
both the routing of vehicles and the loading of goods into them. The separate problems (routing and loading) are already NP\mathcal{NP}-hard, and very difficult to solve in practice. A fortiori their combination is extremely challenging and stimulating. Although
the specific literature is still quite limited, a first attempt to a systematic view of this field can be useful both to academic
researchers and to practitioners. We review vehicle routing problems with two- and three-dimensional loading constraints.
Other combinations of routing and special loading constraints arising from industrial applications are also considered. 相似文献
29.
Tsuyoshi Oshima Iori Yamanaka Anupriya Kumar Junichiro Yamaguchi Taeko Nishiwaki‐Ohkawa Kei Muto Rika Kawamura Tsuyoshi Hirota Kazuhiro Yagita Stephan Irle Steve A. Kay Takashi Yoshimura Kenichiro Itami 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(24):7299-7303
The synthesis and functional analysis of KL001 derivatives, which are modulators of the mammalian circadian clock, are described. By using cutting‐edge C H activation chemistry, a focused library of KL001 derivatives was rapidly constructed, which enabled the identification of the critical sites on KL001 derivatives that induce a rhythm‐changing activity along with the components that trigger opposite modes of action. The first period‐shortening molecules that target the cryptochrome (CRY) were thus discovered. Detailed studies on the effects of these compounds on CRY stability implicate the existence of an as yet undiscovered regulatory mechanism. 相似文献
30.
Hsi WC Kunde GJ Pochodzalla J Lynch WG Tsang MB Begemann-Blaich ML Bowman DR Charity RJ Cosmo F Ferrero A Gelbke CK Glasmacher T Hofmann T Imme G Iori I Hubele J Kempter J Kreutz P Kunze WD Lindenstruth V Lisa MA Lynen U Mang M Moroni A Müller WF Neumann M Ocker B Ogilvie CA Peaslee GF Raciti G Rosenberger F Sann H Scardaoni R Schüttauf A Schwarz C Seidel W Serfling V Sobotka LG Stuttge L Tomasevic S Trautmann W Tucholski A Williams C Wörner A Zwieglinski B 《Physical review letters》1994,73(25):3367-3370